Method of treating piston rings



Jan. 3,41933. M. B. COyERT 1,893,274

mamon oF 'rgmme PIsToN amas Filed Nov. 2s. A1930O I Patented Jan. 3, 1933 UNITED STATES PATENT OFFICE MARTIN B. COVERT, 0F HOLLAND, MICHIGAN ASSIGNOR T0 REN PARTS CORPORA'JION,

-OF HOLLAND, MICHIGAN, A CORPORATION F MICHIGAN IETHOD OF TREATING PISTON RINGS .Application leg November. 26, 1930. -Serial No. 498,282.

This invention particularly relates to the manufacture of piston rings and the like.

It has been found in use of cast iron piston* rings as'heretofore manufactured that warping occurs, and the amount of resultant distortion of the ring depends largely upon the shape of the articleV and thel internal strains that are set up in the process of cooling and also on the temperature of themotor in which the rings are used as well as the vibrations and jars to which the rings are subjected during operationv of the motor. Such warg.

ing or distorting of the rings permitslea age past the same with the resultant detrimental eiects well understood in the art. To obviate such warping it has'been customary to allow the ring castings to age or set after a machining operation but this process may take from siX to eight months or even longer depending almost entirely upon the sizeof the casting and the accuracy that is to be required of the part after the ring is completed. It has been found that unless this is done the finished rings will change shape and size.

The salient object of my invention is to treat piston rings during the manufacture thereof to eliminate strains and irregularities therein to thereby prevent warping and distorting during use and also to very materially articles of this class and in treating or age'- ing them to overcome the warping tendencies. Y

Another object of my invention is to provide a process of treating piston rings and the like to eliminate warping and distorting tendencies therein` which will be simple and rapid to perform and which can be practiced b v manufacturers where time is a material element.

A still further object is to anneal the p ston rings or the like to attain uniformhardness throughout and .to eliminatehard spots whereby machining will be facilitated.

A selected embodiment of the invention is set forth in the following description wherein reference is made to the accompanying drawing in which l Fig. 1 is an elevational view showing-the ring as it appears in the first step 'of the 50 process;

reduce the time required in manufacturing Fig 2 illustrates the ring after splitting thereof; and

Fig. 3 is a partially diagrammatic'view g the heat treating step in the process of manufacture. My improved process of manufacture of piston rings embodies four""main steps or operations.

The first step in the process consists in casting the piston rings in theusual way and these rings are subsequently machined preferably, though not necessarily, to give a rough finish .on the outerperipheries thereof. During such an operatlon a plurality of rings are usualy mounted side by side on a mandrel to expedite the machining. "A ring of this Acharacter is illustrated in Fig. 1 and is indicated by 4.

The second step in the process consists in transversely slitting the rings to form rings of the so-called split type. The rings 4 are slit diagonally, as indicated at 5, in this step of the process. The process as thus far described does not materially differ from the operations heretofore performed in the manufacture of piston rings.

Afterthe machining and splitting operations have been performed the rings are ready for the third step in the process and in this step the rings are mounted on a non-recip-4 rocating mandrel 6 or the like suspended in a heat-treating 'chamber 7 which in the present instance is heated by a burner 8 that extends through an opening in the casing 9 lwhich surrounds thechamber 7. The rings 4 on the mandrel 6 are subjected to a temperature of approximately 1100 Fahrenheit, which is above the temperature to which they are subjected during use, for a period of about thirty minutes. The rings are then permitted to cool before the Afinal machine operations are performed. The time of the exposure of therings to the heat may be lengthened without `cooling steps are removed.

I have found that articles .produced by the above described process may be machined repeatedly without causinIgl .any perceptible warping or distorting, an thus my invention resi es primarily in the heat treatment although the heat treatment is but a step in the process of manufacture. With my improved process it is possible to produce accurate and.

satisfactory rings in three days whereas it would require at least sixty days by the old method andthe resulting product would not be as accurate as that produced by my method. Furthermore, since the rings are heated but once appreciable time is saved in the manufacture. Moreover, the fourth or final step in the process may be performed as soon'as the rings are cooled after completionof the third step. By heating the rings to a temperature above that to which they are subjected in use,

' I eliminate the likelihood of the rings being aiected by engine heat, that is to say, I prevent additional heat treatment of the rings during use thereof.

While I have particularly described my process in connection with the manufacture of piston rings it is to be understood that this is susceptible to other uses and to variation and modification and I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim: l

1. The process of treating cast iron piston rings and the like to prevent warping and distorting'in use, consisting in arranging the articles on a support and subjecting the same to a temperature of approximately 1100 Fahrenheit for a period of about thirty minutes, and in then allowing the rings to cool to permit finishing of said rings to size as soon as they are cooled.

2. The process of manufacturin piston rings consisting in introducing the rings into a chamber and subjecting the rings but a single time to a temperature above that to which they will be subjected during use, and in then allowing the rings to cool Vso that further operations may be performed thereon as soon as they are cooled.

3. The processof treating cast iron piston ringsand the like consisting in subjecting the rings to a temperature of approximately 1100 Fahrenheit to remove hard spots and other irregularities and prevent warping and .distortion in use, and in then allowing the rings to cool to permit inishing of 'said rings to size as soon as they are cooled.

MARTIN B. COVERT. 

